Hobbing grinder and wheel dresser



Feb. 26, 1952 J. J. OSPLACK 2,587,202

HOBBING GRINDER AND WHEEL DRESSER Filed March 5, 1947 5 Sheets-Sheet lFeb 1952 J. J. OSPLACK HOBBING GRINDER AND WHEEL DRESSER 5 Sheets-Sheet2 Filed March 5, 1947 i W 3. m mu :m m0 0 WJ mm m m M i Feb. 26, 1952QSPLACK 2,587,202

HOBBING GRINDER AND WHEEL DRESSER Filed March 5, 1947 5 Sheets-Sheet 3INVENTOR Jase v)? J asp/ac)? Feb. 26, 1952 PLA 2587202 HOBBINC GRINDERAND WHEEL DRESSER Filed March 5, 1947 5 Sheets-Sheet 4 INVENTOR 703302(I 0.530100% BY QM u x Mw -u Z (Luau-v11 ATTORNEYS Feb. 26, 1952 J. J.OSPLACK I 2,587,2Q2

' HOBBING GRINDER AND WHEEL DRESSER Filed March 5, 1947 .5 Sheets-Sheet5 INVENTOR Jbse'pfi J age/aw? Patentecl Feb. 26, 1952 UNITED STATESJoseph J. Osplackg, Detroit Mich.-,\, assignor to Vincox (3'orporation;Detroit,- Mich., acorporae tion oflMichigant.

Applicatio'uMai'ch- 5; 1947 Serial In 7325521 11? Glaims: (CI. 51-95 )1invention; relates: to. abobbing-grinder? and; wheeldresserrfixtureafor: a mcvableetable machine .tool. base-sand" especially 'toxa ifixtureforr attachment .toa movable-tahlemachine toolibasei Oil the typedescribed in o theapplication of Racy: DLIBennett; Serial-No. 498,'76'3, fileduAugust' 16 1943; which; issued: as Patent'No; 2,442,635dated June 1;. 19.48; capable of the precision hobbing ofgears:bygrinding from-ztheblank according. to the method; describedinvxmyt copending application, Ser. No. 650,831; filed). February28,1946; in combination-v with .cooperating'imeans for: preciselydressing the :grinding; wheel.-

Broadly, this; fixture: comprises 1 a vertical: col um'niattachedttotheizmachinei-base and carrying" the grinding wheel: spindle: extending:horizontally perpendicular to the: direction of motion- 0f the movable:talc'leze and capable of adjustment toward andiawayfromxthat table:vertically and driven work-carrying; and wheel dressing por tions;mounted upon. a; common: frame: or base casting: This frame is: carriedby the I movahletable and; supports; the gear.- trainsfrom which bothwork :drive: andf dresser drive 1 receive their driving impulse from};thei grinder wheel spindle" drive. The: whole is so arranged that--w'ork" and dresser: canzbe moved .horizontallywith thetable and: the;spindles vertically: in":. the column while rotating;

One: distinguishing feature:- of this: combined 30 hobbi-ng; grinderand: wheel dressee fixture is' that: the wheeliisi dressed exactly-:-atplace of contact with. thezworkz A furtherfeatureis that-. the:-movement of; the diamonds on the dresser necessary to' produce thecorrect leadof; theiheiica'li hobbing threads on thegrinding"- wheel isproduced by the:movemen t 'of a=rotarydiamond carrier: through aw smallare off its" circleofvrotation and the feed of the diam'ond sautomatically: accomplished during a portion of: that-1rotary pathwhenzither diamondsare-nnot int contact with-'1 the grinding wheel; Thusa" fully; automatic action; is: accomplished without the use. of lead:.screws v and" without 1 the necessity of reversing; the direction v; oftravel i of: the diamonds This constructions: productive-= of the markedsimplification of the-.cdresser meche anism and, because only rotarymotions: are involved, a:- high; degree: of precisionli im themanufacture: of? the machine cam be obtainedat; relatively==lovwcostsIt:fis;'.of: course; .apparent that the theoretical: accuracy: of lead;produced by even'; az-sm-all arc: of: alunifrma rotary: motion 1 is notperfect. But, over that portion of the face:

t0uches':the;:work', the.:deviation fromrtheoreticaltaccuracyiisssd-slightzascto be undetectable in the limits; evennofaclosest manufacturing tolerances; since the wheel rotates in a singleplane and; as::

a 'result'i-only about; threexthreadsare used;

Flora: complete: description: of; my holcbing grinding. and:wheeledresser fixture, reference" is:

made to; the accompanying: drawings; in which: Fig. .1is1;a"perspective;- view; of a movable table:

machine tool base'fitted with the fixturefofemyf invention Fig. 2 is: aclose-up, perspective: view." of; a

portion of; thefixtureillustrating a5 spur gear; in:

grinding: position; and; the: dresser; withdrawn:

7 from contact with the grinding wheeh;

20 .Wheel;

Fig; 4 iswa viewsimilarto' Fig 3 illustrating; the helical" gear in!grinding; position"; and the: dresser portion of r the fixture;withdraw-nefrom: contact with the grinding wheel;

1| Rig: 5-; is: an enlarged view" illustrating: the grinding contactbetween theg-rinding wheel-@anda heI-icaL-gean. of Fig; 4;

Fig. .6, is-a detailed elevationlpartially in section:

showing the mounting; of; the: grinding; wheel:

spindle-,1 spindle slide,- and; spindle; drive. 1R5 the-:- columnsattached; to s the: machine basei and-=7 the Fig,9-/is-:a-'partialwertical sectioni takemon: the

line.9--9 of Figti8;

' FigJLLO is aidetailedzv'iew illustratingithe'z diaa mondwcarriersrofthe dreser; and

Fig ll is a' 'view partially in: section: through the: dresser drivezmechanism illustrating a dressersfeed'.

Referring now to-Fig: 1; the-machine tool lria'sel Axhas aumovablewtable'I 'to wliiclr the frame? of theiz-fixture carrying the dresser unit Iland headstockxspindleil51'are'fastened5 Base A also carries afiixedthereto a vertical column B' on which'ithe fixture ;drive motor M' ismounted on bracket C.

appearsz more clearly in Fig. 6}. grindiiig wheel:- I is mounted onspindle 2 and? driven by motor through v-helt's' 3s Spindle 2 andiparof? the" bobbing: grindingz wheel which actually 551 allel countersh'aft4* are. journalled in spindle slide 5 which is conventionally slidablymounted in column B with its vertical movement controlled by hand wheelW. Gear box l, which forms a part of spindle slide 5, contains geartrain 6 by which the rotation of countershaft 4 is synchronized withrotation of spindle 2. The miter gears 8 transmit power to the verticalspline shaft 9. The spindle slide 5 can thus be moved vertically whileshaft 9 is rotating in synchronism with spindle 2. The lower end ofshaft 9 enters gear box H] which is fastened in a fixed position oncolumn B. V

heierring now more particularly to Figs. 7 and 8, the motion of verticalspline shaft 9 is transmitted through miter gears 5| in gear box Iii tohorizontal spline shaft The splines enable the frame F supportingwork-carrying and wheel-dressing portions of the fixture attached to themovable table T of base A to be moved horizontally during rotation ofshaft Miter gears I2 transmit the revolving motion of shaft H to shaltl3, which is the main drive shaft for both the dresser unit [4 and theheadstock spindle I5.

Taking up first the dresser drive, the dresser unit I4 is driven throughchange gears l5 which transmit the motion of shaft |3 to shaft I1. ShaftI! is keyed to worm l8 which drives the worm wheel [8 fastened tovertical shaft 23 on which the dresser unit [4 is carried. The dresserunit l4 carries two finishing diamonds 2| and 22 spaced apart onopposite sides of and equally distant from the center of shaft 23 and aroughing-in diamond 23 at a like distance from the center of shaft 20.

Referring now to Fig. 3, when the dressing unit is being used to dressthe face of grinding wheel I, the dresser unit I4 is moved horizontallyby motionof table T to a position directly beneath spindle 2. The rateof travel of diamonds 2| and 22 across the face of grinding wheel and,thus, the lead of the hobbing thread to be dressed on that wheel isdetermined by appropriate selection of change gearslfi. That is to saythat, during one revolution of wheel I, diamond 2| or diamond 22, as thecase may be, will be caused to move across the face of wheel I adistance equal to the pitch of the hobbing thread. As has beenpreviously indicated it is, of course, impossible for the circularmotion of the diamond exactly theoretically to equal this pitch but, inthe small segment of are required for this motion, especially at thecenter of the face of the grinding wheel, the actual deviation fromtheoretical lead is negligible.

"As can be seen in Fig. 10, the dresser unit |4 comprises a base member52 aflixed to shaft 20 and to which the finishing-diamonds carrier arm24 is hinged by shaft 25. The diamonds 2| and 22, themselves, arepivotally mounted in holders 54 on carrier arm 24. The profile of thethread form to be dressed on wheel I is determined by the angularadjustment of diamonds 2| and 22 by rotation of holders 54 in carrierarm 24 and by the angular relation of carrier arm 24 to base member 52,which is secured by means of feed dial 26, which controls the setting ofmicrometer screw 21. Proper contact between the micrometer screw 21 andthe end of carrier arm 24 is assured by the tension of spring 53connecting base member 52 to arm 24.

It will be observed that finishing diamonds 2| and 22 are in dressincontact with wheel I alternately and separated by 180 degrees ofrotationpf shaft 20. It will be further observed that finishing diamonds2| and 22 dress opposite faces of the hobbing thread on wheel I and are,therefore, set in angular relation to arm 24 parallel to one another,thus assuring symmetry of opposite faces of the hobbing thread.

The feed of diamonds 2| and 22 by means of micrometer screw 2'! issecured by contact between feed plunger 28 and feed dial 25 (Fig. 2).Feed plunger 28 operates by making friction contact with feed dial 26 ata time in the cycle when neither diamond 2| nor diamond 22 is in contactwith wheel I. This friction contact by rotation of feed dial 25 elevatesmicrometer screw 27 a predetermined amount at each contact until thefull depth of the thread on grinding wheel I is reachedby diamonds "2|and 22. The amount ofthis feed is determined by the sum of theclearances 30 and 3| (Fig. 10), which represent the amount of verticaltravel possible before either feed dial 26 or stop collar 55, affixed tomicrometer screw 27, are brought into contact with the dresserunit basemember 52. From a midpoint in this vertical travel determined by thepitch line of the thread to be dressed on the wheel I, clearance 30 isadjusted to permit the desired diamond travel below pitch line andclearance 3| is adjusted to permit the desired diamond travel abovepitch line. When the full depth of out has been reached, the frictiondrive of feed plunger 28 on feed dial .26 merely slips and the feedconsequently stops.

Inthis connection it will be observed that roughing diamond 23 iscarried in its holder 55 in fixed space relation to dresser unit basemember 52 and is incapable of adjustment to finish the faces of thehobbing thread on wheel I. It is merelyintended to remove at the properlead the relatively large quantity of material necessary to rough in thethread which is later to be finished by diamonds 2| and 22.

Turning now to the work drive especially illustrated in Figs. '7, 8 and9, change gears 32 transmit the rotation of shaft |3 to shaft 33 whichdrives miter gears 34. From miter gears 34 rotation is transmittedthrough spur gears 35 to vertical shaft 35. It will be observed that thevertical arrangement permits the swinging of the entire head stockhousing 31 about the shaft 36 to permit the grinding of a helical gear,as illustrated particularly in Figs. 3, 4 and; 5. Through miter gears38, shaft 36 transmits rotation to shaft 39 which in turn drives mitergears 40 rotating shaft 4|. The change gears 42 transmit the motion ofshaft 4| to shaft 43 which is keyed to worm 44. Worm 44 drives the wormwheel 45 which is fastened to head stock spindle l5. Head stock spindleI5 is provided with a 60 degree center 46 and is arranged to cooperatewith tail stock 41, which is also carried on head stock housing, 31. Aspecial spindle adaptor and support 48 are made for driving eachparticular gear 49, which is the production part to be ground by thefixture. By means of change gears 32 and 42, the speedof the headstockspindle I5 is synchronized with that of wheel I so that, for

each revolution of latter, the former rotates an amount equal to onetooth of the gear 43 to be ground.

As shown in Fig. 8, a stationary diamond 50 is used, mounted on the headstock housing 31 to dress the outside diameter of the wheel I prior toroughing in its thread with diamond 23 and finish dressing itsthreadwith diamonds 2| and in order to describe the complete sequence ofessence-z" operations intendedtoibeacarried out ibysth'eifixe ture ofmy. invention; letituszsuppose:thatiwe: desire to grind .aprecisionhelicalgearzofspecified: helixangle and pitch..

Before placing theworkvin-the headzstock; we: will first set up'changeigears Hitto': synchronizethe rate of rotation ofidresser unit Mwith that" of grinding wheel lso that the distance per revotrlution ofwheel I that eachdiamond1move'sion its circular path equals thelead ofthe-.tlirea'd to be dressed. We wi'll thenzset. up the. change gears 32and 34 to synchronize-thecrate ofz-rotaie tion of head stock spindle i5withvthat ofig'rinde ing'wheel I so that, for eachrevolution off the&Wheel I, the headstock l5 will-turn through an. angle equal to 360degrees divided by the number: of teeth on the finished gear.

By means of movable table T built into base A, We then movediamond 50'into" position for dressing the outside diameter of wheel I, andcomplete this initial step as a handrcontrolled: operation. Itwill.beobservedthat-both head stock l5 and dresser unit l4'rotate in thepredetermined synchronism with Wheel I whenever wheel I is in motion.Having completed the dressing of the outside diameter ofwheel l, themovable table T will be employed to bringdresser unit l4 into a positioninwhich roughingdiamond 23 will rough in the desired hobbingthread. Thatis to say that, in- Fig; 1, the portion of the unit shown attachedto themovable table T of base A will be moved to the left until the path ofrotation of diamond 23 is tangent to a perpendicular plane through thecenter line of spindle 2 at the midpoint of the face of Wheel i. Withdiamonds. 2| and 22 turned in carrier arm 24 to be entirely out ofcontact with wheel I, the roughing-in operation is carried on with handfeed until a satisfactory roughing in of the hobbing thread on the faceof wheel I has been accomplished. I

Thereafter, diamond 23 is withdrawn from possible contact with the faceof wheel l and diamonds 2| and 22 are adjusted to provide theappropriate profile of the thread on the face of wheel I by suitableadjustment of the angle of their holders 54 in carrier arm 24 and byadjustment of the stops controlling feed screw 21. Feed screw 21 is thenwithdrawn by means of feed dial 26 to its lower limit and the mechanismset in motion. The rotation of dresser unit M then causes the finishingdiamonds 2! and 22 to finish dressing the thread of wheel I at the exactpoint in space in which it will grind. The diamonds 2| and 22 cutalternately each 180 degrees of revolution of unit l4, being advanced byfeed screw 2'! one predetermined increment through friction action offeed plunger 28 until the predetermined depth of feed is reached. Foreach pass across wheel I, it will be observed that each diamond dressesa distance of the circumference of the wheel multiplied by the number ofthreads being cut.

The portions of the fixture carried by the movable bed T are thenshifted to the right, in Fig. 1, withdrawing the dresser unit I4 fromcontact with grinding wheel I. The grinding wheel I is raised by meansof hand wheel W and the work to be ground, 49, is placed between headstock adaptor 48 and tail stock 41. Head stock housing 31 is thenadjusted to the appropriate helix angle to be ground and the machine isset in motion. For this operation, automatic horizontal movement of themovable table T is as- Sured by the limit switch mechanism desiga natediS: on: base; A. in. Fig; 1;. As. thexwork is carried backward andforward acrosszfacei' of grinding; wheel I;. the teeth; Off. the; gear;are ground to the: closestzmanufacturing:tolerances;..

, the involuteformoflthe teethLb'eing;ofzcourse;v

assured by the nature of f the relative: motion produced by the hobbing.principle between the; straightfiank of: the thread of.:the face of thegrinding. wheel and. the metal ofthe partitol'be. ground.

I claim:'

1'. A machine tool including; in combination,

a base, a horizontally. movable table-carrie'diby said base, avertical'column affixed to saidbasel extending higher than saidtable, aspindle bear-- ing vertically slidably mountedfin said columnaspindlejournalled in said' be'aringr extending hori zontally' over saidtablegenerally perpendicular to the direction of movement thereof, a motor;a.

power transmission from said motor to said spindle, a grinding wheelhaving a helical-ly threaded peripheral surface on-the end ofsaidspindle above said table, a frame affixed tosaid' table beneath saidwheel, a generally horizontal rotating arm journalledabout a verticalaxis-in and positioned above said frame, at least on wheel dressing toolcarried-on the upp r side-of said arm, synchronizing drive means-fromsaid spindle to said arm, a work holder rotating about a horizontal axismounted on and positioned above said frame, and synchronizing drivemeans from said spindle to said work holder, the several elementsrecited being so positioned and arranged that by movement of said tabledressing contact between said wheel and said tool or grinding contactbetween said wheel and work in said holder at the same point on theperiphery of said Wheel can be effected at will.

2. The combination of claim 1 in which the synchronizing drive meansfrom the spindle to the arm and to the work holder includes a first gearmovable with and driven from said spindle, a vertically externallysplined shaft rotatably mounted in fixed space relation to the column,and a second gear internally splined rotatably mounted in fixed spacerelation to said spindle slidably engaging said splined shaft and inmesh wth said first gear.

3. The combination of claim 1 in which the synchronizing drive meansfrom the spindle to the arm and to the work holder includes a first gearrotatablly mounted in fixed spaced relation to the base driven from saidspindle, a horizontal externally splined shaft driven by said first gearin fixed space relation thereto, and a second gear internally splinedrotatably mounted in fixed space relation to the frame slidably engagingsad splined shaft.

4. The combination of claim 1 in which the synchronizing drive meansfrom the spindle to the arm includes a set of change gears driven fromsaid spindle and driving said arm.

5. The combination of claim 1 in which the synchronizing drive meansfrom the spindle to the work holder includes a set of change gearsdriven from said spindle and driving said work holder.

6. The combination of claim 5 which includes a headstock housing mountedon the frame pivotable in a horizontal plane about a fixed pivot, avertical shaft whose center line would intersect said fixed pivotjournalled in said frame, a first gear journalled in said frame drivingsaid vertical shaft and driven from the spindle and a second gear drivenfrom said vertical shaft driving' the work holder and carried by saidheadstock housing.

7. The combination of claim 1 in which the synchronizing drive meansfrom the spindle to the arm includes a vertical shaft journalled in theframe driven in predetermined timed relation to the rotation of thespindle and the rotating arm includes a base member carried by saidshaft and a plurality of diamonds carried by said base member spacedapart in the same horizontal plane equidistant from the center of saidshaft.

8. The combination of claim 7 which includes a carrier arm hinged at oneend to move in an arc in a vertical plane above the base member, a pairof diamond holders mounted on said carrier arm on opposite sides thereofon a line through the center of the shaft, and a feed screw carried bysaid base member in operative engagement with the other end of saidcarrier arm.

9. The combination of claim 8 which includes a manipulating membercarried by the feed screw and a spring-pressed plunger carried by theframe adapted to make momentary friction contact with said manipulatingmember once during each revolution of the base member.

10. As a sub-combination, a diamond carrier rotatable about an axisperpendicular to a first reference plane, a threaded grinding wheelrtatable about an axis perpendicular to a second reference plane, saidfirst reference plane bein perpendicular to said second reference planeand also perpendicular to a radius of said wheel without intersectingthe axis thereof, andl'a plurality of diamonds carried by saidcarrier'all in the same plane parallel to the first reference plane andall equidistant from the axis of rotation of said carrier, the circularpath of said diamonds being such that a line tangent thereto is parallelto the axis of rotation of said wheel and intersects a tangent to theperiphery thereof, each at their points of tangency.

11. The combination of claim 10 in which the rotation of the wheel issynchronized to the rotation of the carrier so that during onerevolution. of the wheel a point on the circular path of the diamonds inthe vicinity of the intersecting tangents will move a distancesubstantially equal to the pitch of the wheel thread.

JOSEPH J. OSPLACK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,426,630 Simmons Aug. 22, 19221,501,230 Olson July 15, 1924 1,626,232 Gagarin Apr. 26, 192'? 1,642,554Olson Sept. 13, 1927 1,839,693 Miller Jan. 5, 1932 1,842,538 BurgessJan. 26, 1932 2,014,955 Taylor Sept. 17, 1935 2,309,312 Harley et a1Jan. 26, 1943

